The possible link between the estrogens, catecholamines and cyclic AMP accumulation was studied in vitro. Diethylstilbestrol and estradiol but not estriol of 17 alpha-estradiol elicited increase cyclic AMP formation. This stimulation could be blocked by alpha and beta adrenergic blockers and the antiestrogen clomiphene in the female rat. The accumulation of cyclic AMP could also be blocked by slicing the hypothalmus and adding theophylline. Investigations are being continued on the role of these steroids in the catecholamine-cyclic AMP system.